Pseudocholinesterase deficiency

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Pseudocholinesterase deficiency, also called butyrylcholinesterase deficiency, is a condition that is characterized by an increased sensitivity to certain substances, including the medications succinylcholine and mivacurium. These medications may be given during general anesthesia. General anesthesia is typically used during major surgeries and causes a brief period of unconsciousness. Succinylcholine and mivacurium relax the muscles used for movement (skeletal muscles), including the muscles involved in breathing.

Succinylcholine and mivacurium are typically broken down (metabolized) by the body within a few minutes of being administered. However, people with pseudocholinesterase deficiency do not metabolize these medications as quickly, so they remain active longer than usual. As a result, people with pseudocholinesterase deficiency may not be able to move or breathe on their own for a few hours after succinylcholine and mivacurium are administered. Affected individuals must be supported with a machine to help them breathe (mechanical ventilation) until the medications are cleared from the body.

People with pseudocholinesterase deficiency may also have an increased sensitivity to other substances, including cocaine and the local anesthetic procaine. Local anesthetics are used to numb a small area of the body. Affected individuals may also be more sensitive to specific agricultural pesticides.

Because affected individuals typically have no other signs or symptoms, pseudocholinesterase deficiency is usually not discovered until a person has an abnormal reaction to one of these substances.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Variants (also called mutations) in the BCHE gene can cause pseudocholinesterase deficiency. This gene provides instructions for making an enzyme called pseudocholinesterase, also known as butyrylcholinesterase. This enzyme is produced by the liver and circulates in the blood. Pseudocholinesterase is involved in the metabolism of succinylcholine and mivacurium. This enzyme also helps break down other substances, including some local anesthetics and agricultural pesticides.

Some of the gene variants that are associated with pseudocholinesterase deficiency cause cells to produce a version of the enzyme that does not function properly. Other variants prevent the production of any pseudocholinesterase. A lack of functional pseudocholinesterase impairs the body's ability to metabolize certain substances, including the medications succinylcholine and mivacurium. This causes the effects of these substances to last longer than usual.

Some cases of pseudocholinesterase deficiency are not caused by variants in the BCHE gene and are not inherited. In these cases, the condition is acquired and the enzyme's activity is affected by nongenetic factors instead. These factors can include pregnancy; increased age; chronic infections; kidney, liver, or heart disease; malnutrition; major burns; cancer; and certain prescription medications.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

When pseudocholinesterase deficiency is caused by variants in the BCHE gene, the condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell must have a variant to cause the disorder.

Approximately 1 in 500 people have a variant in only one copy of the BCHE gene. These individuals take longer than usual to clear certain substances from the body but typically not as long as those with a variant in both copies of the gene.

Acquired cases of pseudocholinesterase deficiency are not inherited.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Pseudocholinesterase deficiency occurs in approximately 1 in 3,200 to 1 in 5,000 people. It is more common in males than in females. The condition is also more common in the Persian Jewish community, some people of Alaskan Native descent, and White people of European descent.

Which doctor should you see?

The suggested department for discussing Pseudocholinesterase deficiency is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Pseudocholinesterase deficiency. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.